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    <title>Teleportation</title>

    <link href='css/common.css' rel='stylesheet'></link>

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        but is linked by these samples for wider compatibility.-->
    <!--script src='https://cdn.jsdelivr.net/npm/webxr-polyfill@latest/build/webxr-polyfill.js'></script-->
    <script src='js/xrray-polyfill.js' type='module'></script>
    <script src='js/webxr-polyfill.js'></script>

    <script src='js/webxr-button.js'></script>
  </head>
  <body>
    <header>
      <details open>
        <summary>Teleportation</summary>
        <p>
          This sample demonstrates teleporting the viewer by updating the
          XRSession reference space. Select a point on the floor with a
          controller to teleport to it. Select the leftmost box to rotate to the
          left by 30 degrees. Selecting the rightmost box rotates the viewer by
          30 degress to the right. Select the middle box to reset the
          viewer orientation.
          <a class="back" href="./index.html">Back</a>
        </p>
      </details>
    </header>
    <script type="module">
      import {Scene} from './js/cottontail/src/scenes/scene.js';
      import {Renderer, createWebGLContext} from './js/cottontail/src/core/renderer.js';
      import {Gltf2Node} from './js/cottontail/src/nodes/gltf2.js';
      import {QueryArgs} from './js/cottontail/src/util/query-args.js';
      import {FallbackHelper} from './js/cottontail/src/util/fallback-helper.js';
      import {Node} from './js/cottontail/src/core/node.js';
      import {PbrMaterial} from './js/cottontail/src/materials/pbr.js';
      import {BoxBuilder} from './js/cottontail/src/geometry/box-builder.js';
      import {mat4, vec3, quat} from './js/cottontail/src/math/gl-matrix.js';
      import {BoundsRenderer} from './js/cottontail/src/nodes/bounds-renderer.js';

      // If requested, initialize the WebXR polyfill
      if (QueryArgs.getBool('allowPolyfill', false)) {
        var polyfill = new WebXRPolyfill();
      }

      // If requested, don't display the frame rate info.
      let hideStats = QueryArgs.getBool('hideStats', false);

      // XR globals. Several additional reference spaces are required because of
      // how the teleportation mechanic in onSelect works.
      let xrButton = null;
      let xrImmersiveRefSpaceBase = null;
      let xrImmersiveRefSpaceOffset = null;
      let xrNonImmersiveRefSpaceBase = null;
      let xrNonImmersiveRefSpaceOffset = null;
      let xrViewerSpaces = {};

      let trackingSpaceOriginInWorldSpace = vec3.create();
      let trackingSpaceHeadingDegrees = 0;  // around +Y axis, positive angles rotate left
      let floorSize = 10;
      let floorPosition = [0, -floorSize / 2 + 0.01, 0];
      let floorNode = null;

      // WebGL scene globals.
      let gl = null;
      let renderer = null;
      let scene = new Scene();
      let boundsRenderer = null;
      if (hideStats) {
        scene.enableStats(false);
      }
      scene.addNode(new Gltf2Node({url: '../media/gltf/cube-room/cube-room.gltf'}));
      scene.standingStats(true);

      let boxes = [];

      function initXR() {
        xrButton = new XRDeviceButton({
          onRequestSession: onRequestSession,
          onEndSession: onEndSession,
          supportedSessionTypes: ['immersive-vr']
        });
        xrButton.addToHeader();

        if (navigator.xr) {
          requestInlineSession()
          .then((session) => {
            gl.canvas.addEventListener('touchend', () => {
              session.end().then(() => {
                requestInlineSession({ optionalFeatures: ['local-floor'] });
              }, { once: true });
            })
          });
        } else {
          // Still render the initial scene if WebXR is not available.
          initFallback();
        }
      }

      function initFallback() {
        initGL();
        let fallbackHelper = new FallbackHelper(scene, gl);
        fallbackHelper.emulateStage = true;
      }

      function addBox(x, y, z, r, g, b, box_list) {
        let boxBuilder = new BoxBuilder();
        boxBuilder.pushCube([0, 0, 0], 0.4);
        let boxPrimitive = boxBuilder.finishPrimitive(renderer);
        let boxMaterial = new PbrMaterial();
        boxMaterial.baseColorFactor.value = [r, g, b, 1.0];
        let boxRenderPrimitive = renderer.createRenderPrimitive(boxPrimitive, boxMaterial);
        let boxNode = new Node();
        boxNode.addRenderPrimitive(boxRenderPrimitive);
        // Marks the node as one that needs to be checked when hit testing.
        boxNode.selectable = true;
        box_list.push({
          node: boxNode,
          renderPrimitive: boxRenderPrimitive,
          position: [x, y, z]
        });
        scene.addNode(boxNode);
      }

      function addFloorBox() {
        let boxBuilder = new BoxBuilder();
        boxBuilder.pushCube([0, 0, 0], floorSize);
        let boxPrimitive = boxBuilder.finishPrimitive(renderer);

        let boxMaterial = new PbrMaterial();
        boxMaterial.baseColorFactor.value = [0.3, 0.3, 0.3, 1.0];
        let boxRenderPrimitive = renderer.createRenderPrimitive(boxPrimitive, boxMaterial);

        floorNode = new Node();
        floorNode.addRenderPrimitive(boxRenderPrimitive);
        floorNode.selectable = true;
        scene.addNode(floorNode);
        mat4.identity(floorNode.matrix);
        mat4.translate(floorNode.matrix, floorNode.matrix, floorPosition);
      }

      function initGL() {
        if (gl)
          return;

        gl = createWebGLContext({
          xrCompatible: true
        });
        document.body.appendChild(gl.canvas);

        function onResize () {
          gl.canvas.width = (gl.canvas.offsetWidth * window.devicePixelRatio);
          gl.canvas.height = (gl.canvas.offsetHeight * window.devicePixelRatio);
        }
        window.addEventListener('resize', onResize);
        onResize();

        renderer = new Renderer(gl);

        scene.setRenderer(renderer);
        scene.inputRenderer.setControllerMesh(new Gltf2Node({url: '../media/gltf/controller/controller.gltf'}));

        // Create several boxes to use for hit testing.
        addBox(-1.0, 1.6, -1.3, 1.0, 0.0, 0.0, boxes);
        addBox(0.0, 1.7, -1.5, 0.0, 1.0, 0.0, boxes);
        addBox(1.0, 1.6, -1.3, 0.0, 0.0, 1.0, boxes);

        // Represent the floor as a box so that we can perform a hit test
        // against it onSelect so that we can teleport the user to that
        // particular location.
        addFloorBox();
      }

      function onRequestSession() {
        const mode = 'immersive-vr';
        navigator.xr.requestSession(mode, {requiredFeatures: ['local-floor']})
        .then((session) => {
          session.mode = mode;
          xrButton.setSession(session);
          onSessionStarted(session);
        });
      }

      function requestInlineSession(options) {
        return navigator.xr.requestSession('inline', options)
          .then((session) => {
            session.mode = 'inline';
            return onSessionStarted(session);
          });
      }

      function onSessionStarted(session) {

        session.addEventListener('end', onSessionEnded);

        // By listening for the 'select' event we can find out when the user has
        // performed some sort of primary input action and respond to it.
        session.addEventListener('select', onSelect);

        initGL();

        session.updateRenderState({
            baseLayer: new XRWebGLLayer(session, gl)
        });

        session.requestReferenceSpace('local-floor').then((refSpace) => {
          console.log("created local-floor reference space for " + session.mode + " session");
          return refSpace;
        }, (e) => {
          if (!session.mode.startsWith('immersive')) {
            // If we're in inline mode, our underlying platform may not support
            // the local-floor reference space, but a viewer space is guaranteed.
            console.log("falling back to viewer reference space for " + session.mode + "session");
            return session.requestReferenceSpace('viewer').then((viewerRefSpace) => {
              // Adjust the viewer space for an estimated user height. Otherwise,
              // the poses queried with this space will originate from the floor.
              let xform = new XRRigidTransform({x: 0, y: -1.5, z: 0});
              return viewerRefSpace.getOffsetReferenceSpace(xform);
            });
          } else {
            throw e;
          }
        }).then((refSpace) => {
          // Save the session-specific base reference space, and apply the current
          // player orientation/position as originOffset. This reference space
          // won't change for the duration of the session and is used when
          // updating the player position and/or orientation in onSelect.
          setRefSpace(session, refSpace, false);
          updateOriginOffset(session);

          session.requestReferenceSpace('viewer').then(function(viewerSpace){
            // Save a separate reference space that represents the tracking space
            // origin, which does not change for the duration of the session.
            // This is used when updating the player position and/or orientation
            // in onSelect.
            xrViewerSpaces[session.mode] = viewerSpace;
            session.requestAnimationFrame(onXRFrame);
          });
        });

        return session;
      }

      // Used for updating the origin offset.
      let playerInWorldSpaceOld = vec3.create();
      let playerInWorldSpaceNew = vec3.create();
      let playerOffsetInWorldSpaceOld = vec3.create();
      let playerOffsetInWorldSpaceNew = vec3.create();
      let rotationDeltaQuat = quat.create();
      let invPosition = vec3.create();
      let invOrientation = quat.create();

      // If the user selected a point on the floor, teleport them to that
      // position while keeping their orientation the same.
      // Otherwise, check if one of the boxes was selected and update the
      // user's orientation accordingly:
      //    left box: turn left by 30 degress
      //    center box: reset orientation
      //    right box: turn right by 30 degrees
      function onSelect(ev) {
        let session = ev.frame.session;
        let refSpace = getRefSpace(session, true);

        let headPose = ev.frame.getPose(xrViewerSpaces[session.mode], refSpace);
        if (!headPose) {
          console.error("No head pose, ignoring select");
          return;
        }

        // Get the position offset in world space from the tracking space origin
        // to the player's feet. The headPose position is the head position in world space.
        // Subtract the tracking space origin position in world space to get a relative world space vector.
        vec3.set(playerInWorldSpaceOld, headPose.transform.position.x, 0, headPose.transform.position.z);
        vec3.sub(
          playerOffsetInWorldSpaceOld,
          playerInWorldSpaceOld,
          trackingSpaceOriginInWorldSpace);

        // based on https://github.com/immersive-web/webxr/blob/master/input-explainer.md#targeting-ray-pose
        let inputSourcePose = ev.frame.getPose(ev.inputSource.targetRaySpace, refSpace);
        if (!inputSourcePose) {
          console.error("No Input source pose, ignoring select");
          return;
        }

        vec3.copy(playerInWorldSpaceNew, playerInWorldSpaceOld);
        let rotationDelta = 0;

        // Hit test results can change teleport position and orientation.
        let targetRay = new XRRay(inputSourcePose.transform);
        let hitResult = scene.hitTest(targetRay)
        if (hitResult) {
          // Check to see if the hit result was one of our boxes.
          for (let i = 0; i < boxes.length; ++i) {
            let box = boxes[i];
            if (hitResult.node == box.node) {
              // Change the box color to something random.
              let uniforms = box.renderPrimitive.uniforms;
              uniforms.baseColorFactor.value = [Math.random(), Math.random(), Math.random(), 1.0];
              if (i == 0) {
                // turn left
                rotationDelta = 30;
              } else if (i == 1) {
                // reset heading by undoing the current rotation
                rotationDelta = -trackingSpaceHeadingDegrees;
              } else if (i == 2) {
                // turn right
                rotationDelta = -30;
              }
              console.log('rotate by', rotationDelta);
            }
          }
          if (hitResult.node == floorNode) {
             // New position uses x/z values of the hit test result, keeping y at 0 (floor level)
             playerInWorldSpaceNew[0] = hitResult.intersection[0];
             playerInWorldSpaceNew[1] = 0;
             playerInWorldSpaceNew[2] = hitResult.intersection[2];
             console.log('teleport to', playerInWorldSpaceNew);
          } else {
            console.error("No hit");
          }
        }

        // Get the new world space offset vector from tracking space origin
        // to the player's feet, for the updated tracking space rotation.
        // Formally, this is the old world-space player offset transformed
        // into tracking space using the old originOffset's rotation component,
        // then transformed back into world space using the inverse of the
        // new originOffset. This simplifies to a rotation of the old player
        // offset by (new angle - old angle):
        //   worldOffsetNew = inv(rot_of(originoffsetNew)) * rot_of(originoffsetOld) * worldOffsetOld
        //       = inv(rotY(-angleNew)) * rotY(-angleOld) * worldOffsetOld
        //       = rotY(angleNew) * rotY(-angleOld) * worldOffsetOld
        //       = rotY(angleNew - angleOld) * worldOffsetOld
        quat.identity(rotationDeltaQuat);
        quat.rotateY(rotationDeltaQuat, rotationDeltaQuat, rotationDelta * Math.PI / 180);
        vec3.transformQuat(playerOffsetInWorldSpaceNew, playerOffsetInWorldSpaceOld, rotationDeltaQuat);
        trackingSpaceHeadingDegrees += rotationDelta;

        // Update tracking space origin so that origin + playerOffset == player location in world space
        vec3.sub(
          trackingSpaceOriginInWorldSpace,
          playerInWorldSpaceNew,
          playerOffsetInWorldSpaceNew);

        updateOriginOffset(session);
      }

      function updateOriginOffset(session) {
        // Compute the origin offset based on player position/orientation.
        quat.identity(invOrientation);
        quat.rotateY(invOrientation, invOrientation, -trackingSpaceHeadingDegrees * Math.PI / 180);
        vec3.negate(invPosition, trackingSpaceOriginInWorldSpace);
        vec3.transformQuat(invPosition, invPosition, invOrientation);
        let xform = new XRRigidTransform(
          {x: invPosition[0], y: invPosition[1], z: invPosition[2]},
          {x: invOrientation[0], y: invOrientation[1], z: invOrientation[2], w: invOrientation[3]});

        // Update offset reference to use a new originOffset with the teleported
        // player position and orientation.
        // This new offset needs to be applied to the base ref space.
        let refSpace = getRefSpace(session, false).getOffsetReferenceSpace(xform);
        setRefSpace(session, refSpace, true);

        console.log('teleport to', trackingSpaceOriginInWorldSpace);
      }

      function onEndSession(session) {
        session.end();
      }

      function onSessionEnded(event) {
        if (event.session.mode.startsWith('immersive')) {
          xrButton.setSession(null);
        }
      }

      function getRefSpace(session, isOffset) {
        return session.mode.startsWith('immersive') ?
              (isOffset ? xrImmersiveRefSpaceOffset : xrImmersiveRefSpaceBase) :
              (isOffset ? xrNonImmersiveRefSpaceOffset : xrNonImmersiveRefSpaceBase);
      }

      function setRefSpace(session, refSpace, isOffset) {
        if (session.mode.startsWith('immersive')) {
          if (isOffset) {
            xrImmersiveRefSpaceOffset = refSpace;
          } else {
            xrImmersiveRefSpaceBase = refSpace;
          }
        } else {
          if (isOffset) {
            xrNonImmersiveRefSpaceOffset = refSpace;
          } else {
            xrNonImmersiveRefSpaceBase = refSpace;
          }
        }
      }

      function onXRFrame(time, frame) {
        let session = frame.session;
        let refSpace = getRefSpace(session, true);

        let pose = frame.getViewerPose(refSpace);
        scene.startFrame();
        session.requestAnimationFrame(onXRFrame);

        // Update the matrix for each box
        // Only do this when the position is not emulated - this means one can
        // tell if the viewer pose has an emulated position while still in VR.
        if (!pose.emulatedPosition) {
          for (let box of boxes) {
            let node = box.node;
            mat4.identity(node.matrix);
            mat4.translate(node.matrix, node.matrix, box.position);
            mat4.rotateX(node.matrix, node.matrix, time/1000);
            mat4.rotateY(node.matrix, node.matrix, time/1500);
          }
        }

        scene.updateInputSources(frame, refSpace);
        scene.drawXRFrame(frame, pose);
        scene.endFrame();
      }

      // Start the XR application.
      initXR();
    </script>
  </body>
</html>
